Train control



Aug; Is, 1925. 1,550,604

- c. s. BUSHNELL TRAIN CONTRQL Filed April 17, 1922 I n a/r-lmaa/zr/a FIG. 3. 9

1" I I (A (Wmf/jmzl m E OR.

M/ZIQJ Q the railroad track are divided by insulated joints 2 into blocks in the usual way, one block Iwith the adjacent ends of two other blocks H and J being shown. The parts circuits associated with the various blocks are the same, and for convenience will be given like reference characters with distinctive exponents. Each of the blocks is provided with a track battery 3 and a track relay l, the same as in ordinary block signal systems. My invention may be used with or without the usual fixed signals, dependent'upon the type of train control ap 'atile; andl have illustrated such fixed nals 'S conventionally, without attempting to illustrate their well-known control circuits and devices.

The trackway element T of my invention, in general, comprises a magnetic yoke or core and associated coils, and is adapted to influence by. electro-magnet-ic induction a cooperating element on a passing vehicle. In the construction illustrated, the trackway element T comprises a ll-shaped core or yolie 5 of soft iron, preferably laminated, which has one upwardly extending leg in contact with the rail, and another upstanding leg disposed between the rails and provided with an enlarged pole piece 6. The track element is provided with a winding, sh wn as one coil 7 disposed on the yoke, and another coil 8 onthe leg between the track rails. These coils? and 8 are wound and connected in series so that the electro-motive-t'orces generated therein by a change of flux through the yoke 5 are cumulative or additive. This track element T is sui.t-. ably supported on the ties, vith its outside pole piece firmly clamped or otherwise intimately and magnetically connected to the track rails; and inasmuch as the specific construction that would be employed in practice for this purpose would vary to a large ex ent, dependent upon existing worl-zing conditions, no attempt has been made to show in detail any particular form of mounting for the track element.

These trackway elemen s 'l, are intended to transmit controlling duences or impulses to passing at one or more control points in each bloc in accordance with trailic conditions in the next bloclr in advance alone, or both the next block in advance and the co -m. ionding block, dependent upon the ty 1" train control apparatus employed. In the traclrway equip ment shown in Fig. 1, a tracmvay element T is located at the entrance to each block, a short distance in the rear of the insulated joints, the normal direction of trafiic being from left to right, as indicated by the arrow. The coils 7 and 8 or each traclrway element T are connected in series in a normally closed circuit including the front contact 9 of a line relay 10. In the arrangement illustratecl, the controlling circuit for the line relay 10 includes a front contact 11 of the track relay l of the corresponding block and a front contact 12 of the track relay l of the next block in advance, so that the coils ofthe trackway element T atithe en trance of each block are in a closed circuit of low resistance under clear tratlic conditions, but are open-circuited when either the. corresponding block or the next block in acvance is occupied. These various circuits may be readily traced on the drawing, and need not be specifically described.

One particular form or car-carried equipment has been shown in Fig. 2, illustrating itsrelation to the rails and to the trackway clement T. This car equipment comprises a car element l1, having. a yoke 13 and three downwardly extending legs ll, 15 and 16, provided with enlarged pole pieces, the two outside legs 14: and 16 being disposed over the track rails for purposes to be described hereinafter. These outside legs 14 and 16 are provided with coils 17 and 18 connected in series, in a manner so that the magnetomotive-force produced by current passing through these coils will be in the same direction through the yoke, and serve as an exciting winding for the car element L. These coils 17 and 18 are energized from a bat ery 19, and are connected in series with a train control device K and the front contact 20 ot a control relay R. The middle leg 15 of the car element L is provided with a secondary coil 21, which is connected to the windin maintain its front contact closed. This relay is siiown conitionally, but it should be understood that it will, of course, be properly designed in practice so as to be quick acting, immune to jars and vibration, and otherwise possess the desired operating characteristics.

The train control device K may take any one of several different forms, dependent upon the character of the control desired to enforce upon the train. For example, this train control device K has been illustrated as an electro-pneumatic valve which may be used to vent the train pipe directly, or which m be used in any other way to impose a controlling speed by otl con cl devices lecated on the vehicle. T his device K is provided with suitable contacts 26 shown conventionally as an insulated disc and arrows; and these contacts are opened when the device K operates.

Assume a train to be approaching from the left in the block H and that either of the blocks l or J, or both, is occupied, so that the track element T at the entrance to block I will have its windings 7 and 8 opencircuited. As the car with its car equipment in normal condition illustrated in Fig.

of a control relay in series with a battery 22 of suilicient strength to.

2, passes over the track element T, the reluctance through the yoke 13 and the legs 15 and 16 will be changed by the track element, and the magnetic flux through these legs will he suddenly increased at first, and then decreased back to normal, thereby inducing one cycle of alternating current E. M. F. in the secondary coil on the middle leg onthe car element L. This induced E. M. F. either opposes or aids the voltage of the battery 22, dependent upon the direction of winding and the connections of the secondary coil 21 in circuit with said battery. It may be stated here that these connections are preferably made so that the first wave or half cycle of the induced E. M. F.

' will oppose the battery voltage, thereby reducing the current in the winding of the control relay R and causingits armature to drop.

When the armature 20 of the control relay R drops, its front contacts separate and break the normally closed energizing circuit for the train control device K, thereby setting said device into operation and applying the brakes, or otherwise imposing the desired control upon the vehicle. This energiz- .ing circuit may be traced as follows Com mencing at the battery 19, wire 23, front contacts of relay R, wires 24 and 25, contacts 26 of device K closed onlywhen said device is energized, wires 27 and 28, device K, wire 29, primary coil 18, Wire 30, primary coil 17 and wire 31 back to the battery.

The voltage induced in the secondary coil 21 and deenergization of the relay R are only momentary, and the front contacts of said relay close immediately. The energizing circuit for the device K, however, ineludes its own contacts 26, and consequently said device is not reenergized by a closure of the front contacts of the relay.

It is noted here that the dropping of'the relay breaks the primary circuit. This is done because the train control device K is included in the same circuit with the primary coils17 and 18, so that if the current in said primary coils, due to breakage of a wire, depreciation of the battery, or the like, should fall below the value necessary for safe operation, such dangerous condition is automatically detected by reason of the fact that the device K then automatically operates. This safety or checking expedient forms no part of the present invention, but is shown because it is one of the characteristic features of the type of train control system selected to illustrate the naure of this invention.

In order that the car-carried equipment may be brought to its original or normal condition, a reset switch-RS has been provided. This reset switch BS is preferably located in a locked box for which the conductor or some person other than the engineer holds the key, so that it can not be operated without the knowledge of a responsible person. Other expedients, however, not material to the present invention, may be employed for protecting manipulation of this reset switch.

lVhen the reset switch BS is actuated, it establishes a shunt, comprising wires 32' and 33, around the stick contacts 26 of the device K, and since the front contacts of the relay R are closed, having been only momentarily opened, the device K is in this way reenergized. Once the device K is reenergized, it is maintain-ed in that condition by its regular energizing circuit whereupon the reset switch RS may be opened.

The other leg 14 of the car element has been provided in order to guard against rail interference, that is,.to prevent a control influence to be transmitted when passing over a crossing rail. For instance, when the car element L passes over a crossing, rail which side legs and the crossing rail, but practically no change of flux will take prace through the middle leg of the car element L, thus inducing no E. M. F. in the secondary winding. This is accounted for by the fact that the reluctance through the magneticcircuit through the track rail is .muchcless, as compared with the magneto-motive-force therein, than the reluctance through. the individual magnetic circuit through each outside leg and the middle leg. Or, putting it another way, the magneto-motive-force in the middle leg caused by the primary coil 17 is substantially equal and opposite to the magneto-motive-force caused by the other primary coil 18, so that these M. M. F.s are neutralized and thereis no change of flux.

If the car element L passesover. a diagonal rail, a change of reluctance would affect the magnetic circuit of the middle leg and one outside leg before it would affect the mag the track rails, the outside legs 14 and 16 and the yoke 13 of the car element L, thus causing very little, if any, change of flux through the middle leg of the car element. Or stating it another way, the track rails act, so to speak, as extending pole pieces of the diagonal crossing rail, making the equivalent. of a large magnetic body which will bridge the two outside legs 14 and 16 of the car element L simultaneously, thereby acting the same as a crossing rail placed substantially parallel to the ear element L, with the result that has heretofore been explained.

Since the car-carried element L is mounted parallel to the axles of a vehicle, and is necessarily mounted fairly near thereto, it is possible that a conside able amount of flux will pass through the yoke 13 and out side legs it and 16 of the car element through the track rails and the wheels and axle of the vehicle, thus completing a leakag magnetic path which may, to a certain extent, be detrimental to the elliciency of the inductive communicating devices. In order to reduce the efi' ect of such a shunted magnetic circuit, it is proposed to provide a section of track rail opposite to the track element T, which is constructed ot non-magnetic material, such as manganese steel, or the like. Such a construction has been illustrated in Fig. 3, where the track rail section 34 0t non-magnetic material is shown in the line of steel rails directly opposite to the track element T. This construction will interrupt the shunt or leakage magnetic circuit at the time the car element passes over the track element. the ends of this nonmagnetic rail section 34: may be located with respect to the pair of wheels and axle atlording a leakage path for the this: in the car element, in such a way that the interruption of said leakage path by the movement of this pair of wheels and axle on to the non-magnetic rail section will occur at the same instant the car element L is coming within the range of influence of the track element T, thereby adding to the regular increase of flux through the secondary coil 21 caused by the reduced reluctance of the magnetic circuit through said coil. In this way, the change of flux and the induced voltage Will be increased and the impulse materially strengthened.

This invention provides means for inductively communicating influences from the trackway to a vehicle for automatic train control systems, permitting the use of a sub stantial air gap between devices on the vehicle and along the trackway, thereby allowing the track devices to be mounted between the rails and at the same time permitting the flangers of snow plows to clear away the snow between the rails. the track devices comprise an inert element which does not require any energy either when in its effective or ineffective condition, while the track device acts on a car apparatus so as to actuate a train control device, crossing rails and other similar magnetic bodies along the trackway will not efiectively influence said the invention is more general in its application. The particular construction shown and described may be modified and adapted in many respects to suit the particular working conditions encountered; and I desire to have it understood that the illustration and description herein does not exhaust the adaptations and modifications of the means and functions underlying the present invention.

lVhat I claim is 1. Car apparatus for automatic train control systems comprising, a three-legged yoke of magnetic material having its outside legs disposed over-the running rails of the trackway, means for magnetizing said yoke, and means for detecting a change in flux through the middle leg.

2. Influence communicating means for automatic train control systems comprising vehicle carried influence receiving means consisting of a three-legged yoke of magnetic material having its outside legs disposed over the running track rails, normally energized coils on the outside legs of said yoke, means for detecting a change in magnetic flux through the middle leg of said yoke, and a traftlc controlled trackway intluence device for causing a change in the flux through the middle leg of said yoke as the vehicle carried means passes thereover.

3. In an automatic train control system, a car-carried element adapted to be induct-ively influenced from the trackway through an intervening air gap and comprising a core with spaced vertically disposed legs, one of said legs being located directly over one of the track rails on which the car runs, a normally energized primary coil on one of said legs, a secondary coil on the other of said legs, a relay on the car connected to said secondary coil, and a track element arranged to come in superimposed relation with said car element and comprising a magnetic core fastened at one end to said running track rail, a coil on said core, and traflic controlled means for including said coil of the track element in a closed deenergized circuit of low resistance under clear traffic conditions and for putting said coil of the track element 011 open circuit under dangerous traffic conditions.

4-. Car apparatus for automatic train control systems comprising, a three-legged yoke of magnetic material having two of its legs disposed over the running rails of the trackway, oppositely wound primary coils on said two legs, a secondary coil on the third leg, and electroresponsive means having an operating circuit connected to said third leg.

5. Car apparatus for automatic train control systems comprising, a secondary coil, two partial magnetic circuits linking said secondary coil and terminating at points adjacent each of the running rails of the trackway, sources of magneto-motiVe-force in said circuits, and normally energized train control means responsive to a change of flux through said secondary coil.

6. A car-carried influence transmitting device for automatic train control systems adapted to be influenced by a track element of limited extent and comprising, two partial magnetic circuits terminating at points adjacent each of the running rails and having opposing sources of magneto-motiveforce therein, a secondary coil, and electroresponsivemeans influenced by a change of flux through said secondary coil.

7. In an automatic train control system, influence transmitting means comprising, a track elementconstituting an inert magnetic body when in its effective condition, and a car-carried element provided with balancedv partial magnetic circuits each including a portion of a running rail and a source of the running rails, means for magnetizing said yoke with opposite poles at said outside legs, and control means responsive to a change of flux through the middle leg.

9. Influence transmitting means for automatic train control system's comprising, in combination with a three-legged magnetic yoke on a vehicle having its outside legs disposed over the running rails, means for oppositely magnetizing said outside legs to cause flux to pass in opposite directions through said legs, means influenced by a change of flux through the middle leg, and a track element of magnetic material adapted to span the middle leg and one of the'outside legs.

10. In an automatic train control system, the combination with a normally energized control relay on a vehicle, of means on the vehicle for reducing the current in said relay in response to the passage over a magnetic body of limited extent along the trackway, said means comprising two partial magnetic circuits terminating at the running rails and having opposing sources of magneto-motiveforces therein, and a receiving coil acted upon by said sources jointly.

11- Influence communicating means for automatic train control systems comprising, a car element having extending legs, said element being supported from a railway vehiclein a manner to have one of its legs disposed substantially midway between the rails and another leg disposed over a track rail, flux responsive means associated with said car element, and trackway means for causing a change of flux in said element.

12. Influence communicating means for automatic train control systems comprising, a track element having one upstanding leg near a rail of the trackway and extending substantially to the top of said rail and another leg substantially midway between the track rails terminating below the top of said rails, and car-carried influence receiving means adapted to be influenced by said track element.

13. Trackway means for automatic train control systems comprising, a track element of magnetic material extending crosswisebetween the track rails and having upstanding legs, a coil on said element, one of said upstanding legs being rigidly fastened to a track rail of the trackway, the other of said legs between the track rails having its upper end below the level of the tops of said track rails, and means for controlling a circuit through said coil.

14. Trackway means for automatic train control systems comprising, a track element of magnetic material having upstanding legs, pole piecesson the end of said legs, one of said legs being shaped to conform with the contour of a track rail and being rigidly fastened to one of the rails of the trackway.

In testimony whereof I hereby affix my signature.

CHARLES S. BUSHNELL. 

